The present invention relates to a disc brake for a motor vehicle having a housing, a piston which is movable in the housing along a longitudinal axis and a nut-spindle arrangement which acts on the piston or can be brought into engagement with this, wherein the nut-spindle arrangement is arranged in the housing and is workingly supported via a bearing arrangement on a support surface of the housing.
Disc brakes of this kind are already known from the prior art. For example, the nut-spindle arrangement is on the one hand used for an adjusting mechanism in order to compensate for increasing wear at the brake linings so that the air gap of the disc brake can be kept largely constant. On the other hand the nut-spindle arrangement is often also used in modern brake types to implement a parking braking function in addition to compensate for wear. For this purpose the spindle is rotatably driven, so that the nut can be moved axially on the spindle. Following hydraulic biasing of the piston, in order to obtain a braking effect which is adapted to the parking braking action, the nut is moved again accordingly, so that it is again brought into contact with the piston. The piston can subsequently be hydraulically pressure-relieved. However it cannot move back into its starting position, which has no braking action, but is essentially held in the intended parking braking position via the nut of the nut-spindle arrangement. In order to prevent a rotational movement of the nut, either the mating pair of threads between the nut and the spindle is formed in a self-locking manner or the spindle is rotationally fixed.
A solution of this kind is also known, for example, from the prior art according to U.S. Pat. No. 5,348,123. It has become apparent that, in order to prevent undesirable frictional resistances, the spindle is advantageously to be mounted in the housing with low friction levels via a bearing arrangement. Hence the document U.S. Pat. No. 5,348,123 indicates the use of an antifriction thrust bearing as a bearing arrangement of this kind. However problems can occur when supporting the bearing arrangement on the housing. This is due in particular to the fact that the housing is usually made of cast material, in which case the resulting surfaces often have irregularities. If the bearing arrangement bears against an irregular surface of this kind on the housing of the disc brake, different load situations, which may adversely affect the service life of the bearing arrangement, may occur at certain points or in certain areas.